论文标题
富含单一的恒星和银河化学演化 - 观测和理论中可能存在偏见
Mono-enriched stars and Galactic chemical evolution -- Possible biases in observations and theory
论文作者
论文摘要
使用来自金属贫困星的化学丰度模式的长期追捧的目标是了解银河化学演化（GCE）并固定第一颗恒星的性质（POP III）。在这里，我们使用的是14个在LBT处观察到的高分辨率光谱百曲摄影的金属贫困恒星的样品，以得出32个元素（34个限制）的丰度。我们提供了使用局部热力学平衡（LTE）辐射转移代码和1D静静力模型大气的全颗恒星的重采样丰度模式。目前众所周知，1D和LTE的假设可能隐藏了几个问题，从而在我们的解释中引入了关于第一颗恒星和GCE的性质的偏见。因此，我们使用非LTE（NLTE）并使用3D模型大气校正丰度，以呈现出更可靠的模式。为了推断第一颗恒星的性质，我们比较了未发展的，凉爽的恒星，并通过单个事件（“单一富集”）丰富，并进行了一组屈服预测，以限制POP III祖细胞的质量和能量。迄今为止，只有少数真正的第二代单一富集恒星才知道。简单的x^2拟合可能与简单的1D LTE丰度模式一样多地偏向我们的推断质量和能量，因此我们通过考虑稀释和混合的改进的拟合技术进行了研究。我们的样品呈现碳增强的金属贫困（CEMP）恒星，其中一些是有希望的真实第二代（单一富集）恒星。未进化的矮bd+09_2190显示了一个富含单一的签名，该签名与运动学数据相结合，表明它在外晕中移动，并且很可能早已被积聚到银河系中。 POP III祖细胞可能为25.5m，在LTE/NLTE中为0.6 10^51erg（敌人）/19.2m和1.5 foE。最后，我们探索了快速和缓慢的中子捕获元件的主要供体和形成位点。简略
A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the Galactic chemical evolution (GCE) and to pin down the nature of the first stars (Pop III). Here, we use a sample of 14 metal-poor stars observed with the high-resolution spectrograph PEPSI at the LBT to derive abundances of 32 elements (34 including limits). We present well-sampled abundance patterns for all stars obtained using local thermodynamic equilibrium (LTE) radiative transfer codes and 1D hydrostatic model atmospheres. It is currently well known that the assumptions of 1D and LTE may hide several issues, thereby introducing biases in our interpretation as to the nature of the first stars and the GCE. Hence, we use non-LTE (NLTE) and correct the abundances using 3D model atmospheres to present a physically more reliable pattern. In order to infer the nature of the first stars, we compare unevolved, cool stars, enriched by a single event (`mono-enriched'), with a set of yield predictions to pin down the mass and energy of the Pop III progenitor. To date, only few bona fide second generation mono-enriched stars are known. A simple x^2-fit may bias our inferred mass and energy just as much as the simple 1D LTE abundance pattern, and we thus carried out our study with an improved fitting technique considering dilution and mixing. Our sample presents Carbon Enhanced Metal-Poor (CEMP) stars, some of which are promising true second generation (mono-enriched) stars. The unevolved, dwarf BD+09_2190 shows a mono-enriched signature which, combined with kinematical data, indicates that it moves in the outer halo and likely has been accreted onto the Milky Way early on. The Pop III progenitor was likely of 25.5M and 0.6 10^51erg (foe)/19.2M and 1.5foe in LTE/NLTE. Finally, we explore the predominant donor and formation site of the rapid and slow neutron-capture elements. Abridged
